min_* MergeTree table settings

These settings are available in system.merge_tree_settings and are autogenerated from ClickHouse source.

min_absolute_delay_to_close

Minimal absolute delay to close, stop serving requests and not return Ok during status check.

min_columns_to_activate_adaptive_write_buffer

Allow to reduce memory usage for tables with lots of columns by using adaptive writer buffers.

Compared against the number of streams a wide part writes, which can greatly exceed its number of columns: a Map with many buckets, or a deeply nested Array or Tuple, writes many streams for a single column, and one write buffer is allocated per stream.

Possible values:

• 0 - disabled
• 1 - always enabled

min_compress_block_size

Minimum size of blocks of uncompressed data required for compression when writing the next mark. You can also specify this setting in the global settings (see min_compress_block_size setting). The value specified when the table is created overrides the global value for this setting.

min_index_granularity_bytes

Min allowed size of data granules in bytes.

To provide a safeguard against accidentally creating tables with very low index_granularity_bytes.

min_marks_to_honor_max_concurrent_queries

The minimal number of marks read by the query for applying the max_concurrent_queries setting.

Possible values:

• Positive integer.
• 0 — Disabled (max_concurrent_queries limit applied to no queries).

Example

<min_marks_to_honor_max_concurrent_queries>10</min_marks_to_honor_max_concurrent_queries>

min_merge_bytes_to_use_direct_io

The minimum data volume for merge operation that is required for using direct I/O access to the storage disk. When merging data parts, ClickHouse calculates the total storage volume of all the data to be merged. If the volume exceeds min_merge_bytes_to_use_direct_io bytes, ClickHouse reads and writes the data to the storage disk using the direct I/O interface (O_DIRECT option). If min_merge_bytes_to_use_direct_io = 0, then direct I/O is disabled.

min_parts_to_merge_at_once

Minimal amount of data parts which merge selector can pick to merge at once (expert level setting, don’t change if you don’t understand what it is doing). 0 - disabled. Works for Simple and StochasticSimple merge selectors.

min_replicated_logs_to_keep

Keep about this number of last records in ZooKeeper log, even if they are obsolete. It doesn’t affect work of tables: used only to diagnose ZooKeeper log before cleaning.

Possible values:

• Any positive integer.